Abrasives



' Patented May 25, f

UNlTED STATES.

PATENT OFFICE ABEASIVES Coes, Jr., Brookileld, um, to. Norton Company, Worcester, Mass., a corporation of Massachusetts No Drawing. Application July 23, 19.42, Serial No. 452,092

9 Claims.

7 Another object of the invention is to provide a grinding wheel or other solid abrasive article Y which, in various embodiments, may be substituted for abrasive articles bonded with shellac, rubber or phenol-formaldehyde, and which will remove a greater amountof metal 'for a given wheel wear.

vide an ingredient for assisting the conversion of an aromatic amine-aldehyde resin, particularly aniline formaldehyde, to the infusiblecondition. Another object of the invention is to provide a'mixing plasticizer which does not reacttoform water.-

Anotherobiect of the invention is to provide a wetting agent for carrying out the dry granular mix method in the manufacture of the type of abrasive articles indicated of superior quality; Another object is to avoid or prevent swelling of the abrasive article; to permit cold pressing and curing without pressure, and to avoid the formation of any water during the cure. Other objects will be in part obvious or iii-D rt pointed out hereinafter. v

The invention accordingly consists in the features of construction, combinations of elements; arrangements of parts, and in the several steps and relation and order or each of said steps to -45 one or more of the others thereof, all as will be illustratively described herein, and the scop of the application of which will be indicated in I provide a quantity of a primary aromatic amine, such as aniline, ortho, meta or para toluiso dine, or diamino diphenyl-methane; and a quana quantity of one or more organic compoimds. contsininga halogen selected from the-group capable of splitting oif hydrogen halide at elevated temperatures and/or of alkylating an arcmatic amine polymer, providing cross links connecting amine groups of the chains. The aromatic amine whichI now prefer to use is aniline. Aniline I NH:

or one of the other aromatic amines mentioned,

a or mixtures of two or'more of such amin is reacted with formaldehyde HCHO in the presence of a strong acid to produce a long chain polymer which, when an excess of formaldehyde.

above the stoichlometric proportions is used, for example, 20% excess, has adjacent chains connected with methylene CHrgroups to form Another object the invention is to 6 a tough, heat resistant, semi-thermoplastic resin. I may add some of the formaldehyde after the initial condensation, in the" form of paraformaldehyde, or by the addition of he rs-methylene-tetramine. i a

As examples of the halogenated organic compound, I may use any of polyvinyl chloride, polyvinylidene dichloride, rubber hydrochloride, chlorinated rubber, chlorinated polyisobutylene; any chlorine, bromine oriodine substituted parafilne hydrocarbon, such as hexa chlor ethane. tetra chlor pentane,1,2,diiodo ethane. beta butylene bromide, partly chlorinated eicosane, or any aliphatichalohydrin or not more than six carbon atoms, such as any of the amylene chlor- 'are cheaper and more readily available than the brominated or iodated compounds, but the latter two give effective results. The fluorinated' compounds are rejected because they are too stable' and will not alkylate the polymer. However,-

described, the halogenated organic compoun may be omitted altogether.

Since the invention relates to grinding wheels and other solid abrasive compositions and articles, I provide a quantity of abrasive grain. Any abrasive grain may be used, for-example, any

' of. the varieties of alumina, such as emery, corundum. dense "regular" fused alumina, porous white of chlorine, bromine and iodine and II alum'iaarsil wn carbide and rv a d been used as this plasticizer-wettant.

carbides; quartz; glass; garnet; or. diamondsr Two or more of these abrasives may be mixed, if desired.

Manufacturers usually prefer to use the dry I mix thus produced, the top plate is inserted,

the mold is closed" by means of an hydraulic press, the mold is then stripped, the.green wheel is taken to an oven and (at the same time as hundreds or thousands of others of varying sizes, shapes and compositions) it is cured to' make the final composition and, after truing or shaving," the final article. This method, in contradistinction to the use-of the hot press with or without the autoclave and vice versa, has the advantage that ordinary ovens, in which thousands of "green wheels can be stacked, are used; the hydraulic press is tied up by a given wheel for thirty seconds instead of thirty minutes, and the press need have no heated platens. This wetting of the abrasive grains by a liquid is called plasticizing." It is preferred that the wettant be a solvent for the resin.

In the commercial manufacture of anilineformaldehyde resin bonded grinding wheels and other solid abrasive products, only furfural has (Other aromatic-amine-aldehyde polymers have not been used commercially for the manufacture of grinding wheels and other solid abrasive products so far asI am aware). The furfural cross links the polymer and, therefore, converts it to the infusible" condition. A stoichiometric quantity of aniline and formaldehyde condensed in the presence of a strong acid is believed to produce a resin which is structurally represented thusi G-N C-N' tc. Q. U Q I Such a resin cross-linked with furfural is believed to be represented thus:

H H H l without the use of other wettant-plasticizers,

such as furfural, but at present I prefer to use them alone. Thus, I may use di-2chlorethyl phthalate; this ester is:

C 00-- CH:- C'Hs-cl COO-CHr-CHr-Cl Or I may use di-2chlorethyl maleate; this ester is:

' H-COO-Ciiz-Ciir-Ci Y cn-coo-cm-cm-cx Or I mayuse di-2chlorethyl succinate; this ester is: cm-coo-crn-m Hr-COO-CHz-Cl I believe the cross-linking thereby of the aniline-formaldehyde polymer is as shown by the following:

I H\ /Cl 26H: CH:

0! (M8188CB)CIH2 It will be noted that chlorine now appears in the amino group. When a grinding wheel according to the invention is used to grind, the heat generated by grinding (which may reach 500 C. or more and is a higher heat than generated in most sanding operations with sandpaper or the like) releases hydrogen chloride at the grinding line which appears to have a pronounced effect upon the grinding operation, preventing or at least minimizing loading" and assisting in the cutting action by making the metal chips more brittle.

In the making up of abrasive wheels or other abrasive articles, according to my invention, I

am enabled to achieve also other advantages; for example, the green wheel or other shape of v abrasive body does not have to be pressed and heat-cured at the same time and on the contrary, after shaping it in any suitable way, it

can be heat-treated for a suitable length of time, as in an oven, thus making it possible to avoid tying up expensive hot-press equipment. Moreover, abrasive wheels made according to my invention may be given, in general, the general characteristics of rubber-bonded wheels and thus may serve for grinding ,purposes where such characteristics are required or desired.

' However, my invention also consists in the discovery that such esters as the above-mentioned ones function as good solvents or plasticizers or hardening agents for aromatic amine formaldehyde resins, with or without fillers, and thus articles other than abrasive bodies may be made,

the final resin product being tough and of suitand others of which are' mentioned later hereinafter; thus, for example, these esters make available, in the final cross-linking with the abovementioned polymer, of hydrogen chloride and moreover-in a manner to bring about its liberation at the grinding line under the heat effect there present, as mentioned above.

Insofar as I am aware, these esters are also new rials.

resulting in a' dry granular-mix.

is'th'en worked on differential mixing rolls until compositions of matter and a preferred or illustrative method of deriving them may be asfollows:

Thus, as to di-2chiorethyl phthalate, I may start with a mixture of 148 grams of phthalic anhydrlte (1 moi) and 320 grams of ethylene chlorhydrine (4 mols) and heat it with 10 grams of p. toluene sulphonic acid; the latter I believe acts as a catalyst. The mixture is heated at such a rate, as in a flask provided with a short distillation column, that liquid is distilled at the rate of about 1 drop per 5 seconds. Heating is contlnued until the temperature in the boiling liquid rises to about 175 C. (about 8 hours). The mixture is then cooled, and is then neutraiized with sodium carbonate, and washed with water, then dried, for example, over sodium sulphate. The ester so produced may be further purified as by distillation at reduced pressure, but I find it is suflicient merely to heat the product at 100 C. under a pressure of millimeters until all traces of volatile impurities are removed, illustratively for a period of about 4 hours. The product is a slightly colored, heavy liquid and has amild odor. It is a good solvent for aniline formaldehyde resins.

Di-2chlorethyl .maleate and dl-2chlorethyl succinate may be prepared in the same way and they too are good solvents for aniline formaldehyde. In using them with aldehyde resins, with or without fillers or with orwithout abrasive grains, the following several examples as to the makingof abrasive wheels will be illustrative: I

Example I 525 grams of #46 grit Alundum abrasive grains are wet with 20 cc. of di-2chlorethyl phthalate, and here I find that the ester'is a ready and good wettant for the grains; thereto I add 165 grams of a mixture, by volume, of of an aniline formaldehyde resin, 30% of cryollte,

and 5% of soluble anhydrite, and effect a good admixture or stirring thereof, thereby arriving at a so-called "dry granular mix.f The mix is now spread in a 6" mold (where a grinding wheel is to be made), and pressed to a pore volume of '15 percent; this can be done cold or at room 1 temperature. The "green" wheel is then stripped from the mold, and placed in an oven for heat treatment and curing. The initial curing temperature is about C. and the temperature is raised gradually to about 175 C. over a. period of 4 hours, and then kept at about that temperature for 2 hours, and then slowly cooled.

As to the other esters, the same procedure can be followed, using the same proportions of mate- Example 11 525 grams of. #80 grit""Alundum" abrasive grains are wet with 25 cc. of di-2chlorethyl phthaiate and thereto is added, with thorough stirring or mixing, grams of a mixture, by volume, of 65% of an aniline formaldehyde resin, 30% of 'cryolite, and 5% of soluble anhydrite, The latter a sheet is formed which is passed through caiendar rolls to achieve the desired thickness, in this instance is". Out of that sheet 'a 12" disk is cut and the disk is then placed in an oven and cured as described in the foregoing Example I.

As for the other esters, a similar procedure may be employed, using the same proportions of materials.

A wheel made according to Example .11 was tested on cold rolled steel and it showed an areal wheel wear of 0.062 square inch per cut, running wet. and of 0.093 square inch per cut,

running dry, indicating a range of durability like that of rubber-bonded wheels.

a A wheel made according to Example I was tested as a portable snagging wheel with good results; its resiliency was of such an order as to greatly facilitate manual control of the position-- ing or movement of the wheel and the pressure of its application and gave the wheel a free cutting and smooth action. According to certain prior practices,'diflicuities are encountered during heat treatment or curing, due to the fact that. swelling occurs; such swelling usually results from the formation of water and I is aggravated by the conversion of water or possibly also of other constituents into vapors, under the action of the heat treatment. But according to my invention such disadvantages and defects are successfully overcome and I find that, in-

practicing my invention, no such swelling occurs; this is due to the fact that no water or other liquid or vapors thereof, as would cause swelling, duringthe heat treatment or curing, are formed.

I make no claim herein to the resinous compo-' sitions or method of making the same or'to the piasticizer or hardening agent inasmuch as such subject matter is disclosed and claimed in my co-' pending application Serial No. 452,093, filed of even date herewith.

It will thus be seen that there has been provided by this invention, an article, a composition and a method in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As various possible embodiments might be made of the mechanical features of the above invention and as the art herein described might be varied in various parts, all without departing from the scope of the invention, it is to bev understood that all matter hereinbefore set forth is to be inter-v limiting sense.

other abrasive body comprising wetting abrasive grain with a grain-wettant and resin-hardeningagent selected from the group consisting of di- 2ehlorethyl phthalate, di-2chlorethyl maleate and di-2chlorethyl s'uccinate, mixing therewith amine formaldehyde and thereby producing a 'dry granular mix, shaping the mix to the .desired form, and then curing it at resin-curing temperature. I I

3. The method of making agrinding wheel or other-abrasive body comprising wetting abrasive grain with a grain-wettant and resin hardening agent selected from the group consisting of di- 7 2chlorethyl phthalate, di-2chlorethy1 maleate and di-2chlorethyl succinate, mixing therewith amine formaldehyde resin and thereby producing a dry granular mix, working the mix into sheet form of the desired thickness and cutting out of the latter the desired configuration or shape, and

then heat-treating the latter at resin-curing temperature.

4. A grinding wheel or other abrasive body comprising abrasive grains bonded with the reaction product under heat treatment of amine formaldehyde resin and a grain-wetting and resin-hardening agent selected from the group consisting of di-2chlorethyl phthalate, di-2chlorethyl maleate, and di-2chlorethyl succinate.

5. A grinding wheel or other abrasive body comprising abrasive grains bonded with a bond that comprises the reaction product under heat treatment of a grain-wetting and resin-hardening agent selected from the group consisting of dl-2chlorethyl phthalate, di-2chlorethyl maleate, and di-Zchlorethyl succinate, which agent initially wets the grains and which-is also a resinhardening agent, and aniline formaldehyde resin.

6. The. method of making an abrasive wheel or .other abrasive body which comprises making a mix comprising abrasive grain and resin and a grain-wetting and resin-hardening agent selected from the group consisting of di-2chlorethyl 7. The method of making an abrasive-wheel or other abrasive body which comprises making a v mix comprising abrasive grain and resin and a grain-wetting and resin-hardening agent selected from the group consisting of di-2chlorethyl phthalate, di-2chlorethyl maleate. and di-2chlorethyl succinate, shaping the mix to the desired conformation of the abrasive article and compacting it to the desired extent, and'thereatter subjecting it to heat treatment for curing.

8. The method of making an abrasive wheel or other abrasive body which comprises making a mix comprising abrasive grain and resin and a grain-wetting and resin-hardening agent selected from the group consisting of di-2chlorethyl.

other abrasive body which comprises making a mix comprising abrasive grain and resin and a grain-wetting and resin-hardening agent selected from the group consisting of di-Zchlorethyl phthalate, di-2chlorethyl maleate, and di-2chlorethyl succinate. working the mix into sheet form of the desired thickness, conforming it to the desired shape of abrasive article, and then heattreating it to cure the resin and bond the abrasive grain together.

LORING COES, Ja. 

